function y = qf1(x)
% Quadratic QF1 Function  
%x0=[1,1,...1].  
%fmin=n/2
%Author:shi yangyang
n=length(x);
y=ones(1,n);
for i=1:1:n
    y(i)=0.5*i*x(i)*x(i);
end
y=sum(y)-x(n);
